Diets and supplements

Much life extension research focuses on nutrition—diets or supplements—as a means to extend lifespan, although few of these have been systematically tested for significant longevity effects. The many diets promoted by anti-aging advocates are often contradictory. Two diets with different approaches and some support from scientific research are the Paleolithic diet and Caloric restriction.[6][7][8][9]

The free-radical theory of aging suggests that antioxidant supplements, such as Vitamin C, Vitamin E, Q10, lipoic acid, carnosine, and N-acetylcysteine, might extend human life. However, combined evidence from several clinical trials suggest that β-Carotene supplements and high doses of Vitamin E increase mortality rates.[10] Other substances proposed to extend lifespan include oxytocin, insulin, human chorionic gonadotropin (hCG), and erythropoietin (EPO). Resveratrol is a sirtuin stimulant that appears to extend lifespan in simple organisms such as nematodes[11] and short-lived fish.[12]

Some supplements, including the minerals selenium[13] or zinc[14][15] have been reported to extend the lifespan of rats and mice, though none has been proven to do so in humans, and significant toxic effects were observed. Metformin[16] may also extend life span in mice.

[edit]Hormone treatments

The anti-aging industry offers several hormone therapies. Some of these have been criticized for possible dangers to the patient and a lack of proven effect. For example, the American Medical Association has been critical of some anti-aging hormone therapies.[1]

Even if some recent clinical studies have shown that low-dose GH treatment for adults with GH deficiency changes the body composition by increasing muscle mass, decreasing fat mass, increasing bone density and muscle strength, improves cardiovascular parameters (i.e. decrease of LDL cholesterol), and affects the quality of life without significant side effects.[17][18][19] The evidence for use of growth hormone as an anti-aging therapy is mixed and based on animal studies. An early study suggested that supplementation of mice with growth hormone increased average life expectancy.[20] Additional animal experiments have suggested that growth hormone may generally act to shorten maximum lifespan; knockout mice lacking the receptor for growth hormone live especially long.[21] Furthermore, mouse models lacking the insulin-like growth factor also live especially long and have low levels of growth hormone.[21]

[edit]Scientific controversy regarding anti-aging nutritional supplementation and medicine

Some critics dispute the portrayal of aging as a disease. For example, Leonard Hayflick, who determined that fibroblasts are limited to around 50 cell divisions, reasons that aging is an unavoidable consequence of entropy. Hayflick and fellow biogerontologists Jay Olshansky and Bruce Carnes have strongly criticized the anti-aging industry in response to what they see as unscrupulous profiteering from the sale of unproven anti-aging supplements.[3]

[edit]Ethics and politics of anti-aging nutritional supplementation and medicine

Politics relevant to the substances of life extension pertain mostly to communications and availability.[citation needed]

In the United States, product claims on food and drug labels are strictly regulated. The First Amendment (freedom of speech) protects third-party publishers' rights to distribute fact, opinion and speculation on life extension practices. Manufacturers and suppliers also provide informational publications, but because they market the substances, they are subject to monitoring and enforcement by the Federal Trade Commission (FTC), which polices claims by marketers. What constitutes the difference between truthful and false claims is hotly debated and is a central controversy in this arena.[citation needed]

[edit]Proposed strategies of life extension

[edit]Nanotechnology

Future advances in nanomedicine could give rise to life extension through the repair of many processes thought to be responsible for aging. Raymond Kurzweil, a futurist and transhumanist, believes that advanced medical nanorobotics could completely remedy the effects of aging by 2030.[22]

[edit]Cloning and body part replacement

Some life extensionists suggest that therapeutic cloning and stem cell research could one day provide a way to generate cells, body parts, or even entire bodies (generally referred to as reproductive cloning) that would be genetically identical to a prospective patient. Recently, the US Department of Defense initiated a program to research the possibility of growing human body parts on mice.[23] Complex biological structures, such as mammalian joints and limbs, have not yet been replicated. Dog and primate brain transplantation experiments were conducted in the mid-20th century but failed due to rejection and the inability to restore nerve connections. As of 2006, the implantation of bio-engineered bladders grown from patients' own cells has proven to be a viable treatment for bladder disease.[24] Proponents of body part replacement and cloning contend that the required biotechnologies are likely to appear earlier than other life-extension technologies.

The use of human stem cells, particularly embryonic stem cells, is controversial. Opponents' objections generally are based on interpretations of religious teachings or ethical considerations. Proponents of stem cell research point out that cells are routinely formed and destroyed in a variety of contexts. Use of stem cells taken from the umbilical cord or parts of the adult body may not provoke controversy.[25]

The controversies over cloning are similar, except general public opinion in most countries stands in opposition to reproductive cloning. Some proponents of therapeutic cloning predict the production of whole bodies, lacking consciousness, for eventual brain transplantation.

[edit]Cryonics

Main article: Cryonics

For cryonicists (advocates of cryopreservation), storing the body at low temperatures after death may provide an "ambulance" into a future in which advanced medical technologies may allow resuscitation and repair. They speculate cryogenic temperatures will minimize changes in biological tissue for many years, giving the medical community ample time to cure all disease, rejuvenate the aged and repair any damage that is caused by the cryopreservation process.

Cryonicists do not believe that legal death is "real death" because stoppage of heartbeat and breathing—the usual medical criteria for legal death—occur before biological death of cells and tissues of the body. Even at room temperature, cells may take hours to die and days to decompose. Although neurological damage occurs within 4–6 minutes of cardiac arrest, the irreversible neurodegenerative processes do not manifest for hours.[26] Cryonicists state that rapid cooling and cardio-pulmonary support applied immediately after certification of death can preserve cells and tissues for long-term preservation at cryogenic temperatures. People, particularly children, have survived up to an hour without heartbeat after submersion in ice water. In one case, full recovery was reported after 45 minutes underwater.[27] To facilitate rapid preservation of cells and tissue, cryonics "standby teams" are available to wait by the bedside of patients who are to be cryopreserved to apply cooling and cardio-pulmonary support as soon as possible after declaration of death.[28]

No mammal has been successfully cryopreserved and brought back to life, and resuscitation from cryonics is not possible with current science. Some scientists still support the idea based on their expectations of the capabilities of future science.[29][30]